Joint transmission of precoded and unprecoded sounding reference signals in uplink

ABSTRACT

Both precoded sounding reference signals (SRS) and unprecoded SRS are transmitted from a UE to an eNB. The UE may transmit both in the same subframe using either TDM or FDM. Or the UE may transmit each in different subframes from each other. The eNB uses some combination of the precoded SRS and the unprecoded SRS in scheduling resources for the UE. The eNB may also provide instruction to the UE for PUSCH precoding for data transmission. The eNB may signal the UE to use the same precoding as for the precoded SRS. The eNB may instead signal the UE to use different precoding by including the precoding information or delta information between the precoding used for the precoded SRS and the selected precoding for the PUSCH data.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a Divisional Application of U.S.Non-Provisional application Ser. No. 15/689,476 filed Aug. 29, 2017,which claims priority to and the benefit of the U.S. Provisional PatentApplication No. 62/402,141, filed Sep. 30, 2016, each of which is herebyincorporated by reference in its entirety as if fully set forth below inits entirety and for all applicable purposes.

TECHNICAL FIELD

Aspects of the present disclosure relate generally to wirelesscommunication systems, and more particularly, to transmitting bothprecoded sounding reference signals and unprecoded sounding referencesignals from a user equipment, where the eNodeB may use some combinationof both in scheduling resources.

INTRODUCTION

In wireless communication networks, sounding reference signals aretransmitted in the uplink (UL) for use by base stations or eNodeBs (eNB)for a variety of aspects. Some of these include, for example, downlinkscheduling, uplink scheduling (e.g., resource block allocation, rankassignment, modulation and coding scheme, etc.), and coordinatedmultipoint processing to name a few examples.

In current approaches, sounding reference signals (SRS) are unprecoded,meaning that the transmitting user equipment (UE) has not used beamsteering to manipulate the antennas in a multiple input/multiple output(MIMO) system with particular weights to influence the radiation patternfrom the UE. Further, precoded SRS are not envisioned as being used withunprecoded SRS. This results in reduced UL performance given the lack ofeither aspect of information when only the other is used.

As a result, there is a need for techniques to allow providing both SRStypes so as to improve UL efficiency with increased flexibility at theeNB.

BRIEF SUMMARY OF SOME EXAMPLES

The following summarizes some aspects of the present disclosure toprovide a basic understanding of the discussed technology. This summaryis not an extensive overview of all contemplated features of thedisclosure, and is intended neither to identify key or critical elementsof all aspects of the disclosure nor to delineate the scope of any orall aspects of the disclosure. Its sole purpose is to present someconcepts of one or more aspects of the disclosure in summary form as aprelude to the more detailed description that is presented later.

In one aspect of the disclosure, a method is provided that includesgenerating, by a first wireless communications device, a precodedsounding reference signal (SRS). The method further includes generating,by the first wireless communications device, an unprecoded SRS separatefrom the precoded SRS. The method further includes transmitting, by thefirst wireless communications device, the precoded SRS and theunprecoded SRS to a second wireless communications device via an uplinkchannel.

In an additional aspect of the disclosure, a method is provided thatincludes receiving, by a first wireless communications device, aprecoded sounding reference signal (SRS) from a second wirelesscommunications device. The method further includes receiving, by thefirst wireless communications device, an unprecoded SRS separate fromthe precoded SRS from the second wireless communications device. Themethod further includes determining, by the first wirelesscommunications device, a resource scheduling for the second wirelesscommunications device based on a combination of the precoded SRS and theunprecoded SRS.

In an additional aspect of the disclosure, an apparatus is provided thatincludes a processor configured to generate a precoded soundingreference signal (SRS). The processor is further configured to generatean unprecoded SRS separate from the precoded SRS. The apparatus furtherincludes a transceiver configured to transmit the precoded SRS and theunprecoded SRS to a wireless communications device via an uplinkchannel.

In an additional aspect of the disclosure, an apparatus is provided thatincludes a transceiver configured to receive a precoded soundingreference signal (SRS) from a wireless communications device. Thetransceiver is further configured to receive an unprecoded SRS separatefrom the precoded SRS from the wireless communications device. Theapparatus further includes a processor configured to determine aresource scheduling for the second wireless communications device basedon a combination of the precoded SRS and the unprecoded SRS.

Other aspects, features, and embodiments of the present invention willbecome apparent to those of ordinary skill in the art, upon reviewingthe following description of specific, exemplary embodiments of thepresent invention in conjunction with the accompanying figures. Whilefeatures of the present invention may be discussed relative to certainembodiments and figures below, all embodiments of the present inventioncan include one or more of the advantageous features discussed herein.In other words, while one or more embodiments may be discussed as havingcertain advantageous features, one or more of such features may also beused in accordance with the various embodiments of the inventiondiscussed herein. In similar fashion, while exemplary embodiments may bediscussed below as device, system, or method embodiments it should beunderstood that such exemplary embodiments can be implemented in variousdevices, systems, and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary wireless communication environmentaccording to embodiments of the present disclosure.

FIG. 2 is a block diagram of an exemplary wireless communication deviceaccording to embodiments of the present disclosure.

FIG. 3 is a block diagram of an exemplary wireless communication deviceaccording to embodiments of the present disclosure.

FIG. 4 is a block diagram illustrating an exemplary transmitter andreceiver system, such as eNodeB and user equipment, in accordance withvarious aspects of the present disclosure.

FIG. 5A is a block diagram of an exemplary uplink frame structureaccording to embodiments of the present disclosure.

FIG. 5B is a block diagram of an exemplary uplink control messagestructure according to embodiments of the present disclosure.

FIG. 5C is a block diagram of an exemplary uplink control messagestructure according to embodiments of the present disclosure.

FIG. 6 is a flowchart illustrating an exemplary method for wirelesscommunication in accordance with various aspects of the presentdisclosure.

FIG. 7 is a flowchart illustrating an exemplary method for wirelesscommunication in accordance with various aspects of the presentdisclosure.

DETAILED DESCRIPTION

The detailed description set forth below, in connection with theappended drawings, is intended as a description of variousconfigurations and is not intended to represent the only configurationsin which the concepts described herein may be practiced. The detaileddescription includes specific details for the purpose of providing athorough understanding of the various concepts. However, it will beapparent to those skilled in the art that these concepts may bepracticed without these specific details. In some instances, well-knownstructures and components are shown in block diagram form in order toavoid obscuring such concepts.

The techniques described herein may be used for various wirelesscommunication networks such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, LTEnetworks, GSM networks, and other networks. The terms “network” and“system” are often used interchangeably. A CDMA network may implement aradio technology such as Universal Terrestrial Radio Access (UTRA),cdma2000, etc. UTRA includes Wideband CDMA (WCDMA) and other variants ofCDMA. CDMA2000 covers IS-2000, IS-95, and IS-856 standards. A TDMAnetwork may implement a radio technology such as Global System forMobile Communications (GSM). An OFDMA network may implement a radiotechnology such as Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB),IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, etc.UTRA and E-UTRA are part of Universal Mobile Telecommunication System(UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are newreleases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSMare described in documents from an organization named “3rd GenerationPartnership Project” (3GPP). CDMA2000 and UMB are described in documentsfrom an organization named “3rd Generation Partnership Project 2”(3GPP2). The techniques described herein may be used for the wirelessnetworks and radio technologies mentioned above as well as otherwireless networks and radio technologies, such as a next generation(e.g., 5th Generation (5G)) network.

Further, devices may also communicate with one another using variouspeer-to-peer technologies such as LTE-Direct (LTE-D), Bluetooth,Bluetooth Low Energy (BLE), ZigBee, radio frequency identification(RFID), and/or other ad-hoc or mesh network technologies. Embodiments ofthis disclosure are directed to any type of modulation scheme that maybe used on any one or more of the above-recited networks and/or thoseyet to be developed.

Embodiments of the present disclosure introduce systems and techniquesto transmit both precoded sounding reference signals and unprecodedsounding reference signals from a UE to an eNB, where the eNB may usesome combination of both in scheduling resources for the UE.

For example, a UE may include both precoded SRS as well as unprecodedSRS in UL transmissions to an eNB (e.g., whether in periodic oraperiodic SRS uses). The precoding may involve weighting differentantennas of a UE different amounts, so as to cause the UE to steer itsradiation pattern, or beam, in a particular direction. The unprecodedSRS applies equal beam weights to each antenna of the UE. In someexamples, the UE may make the determination of the specific precoding toapply to the SRS, such as based on DL reference signals from the eNB. Inother examples, the UE may receive instruction from an eNB on aprecoding to apply for an SRS.

The UE transmits the precoded SRS and the unprecoded SRS in the UL tothe eNB. For example, the UE may use a time division multiplexing (TDM)approach, such that both precoded SRS and unprecoded SRS are included ina same subframe, each using the same tone or band of tones at differenttime slots (or symbol periods) in the same subframe. As another example,the UE may use a frequency division multiplexing approach, such thatboth the precoded SRS and unprecoded SRS are included in a samesubframe, at the same time slot but using different tones (orsubcarriers) with respect to each other. As another example, the UE mayuse different resource slots (time and/or frequency) in differentsubframes to transmit the precoded SRS and unprecoded SRS—thus, one ofthe SRS (e.g., precoded) may be transmitted in a first subframefollowed, in a later subframe, by the other SRS (e.g., unprecoded, orvice versa).

The eNB receives both SRS types after transmission from the UE. Withboth precoded SRS and unprecoded SRS, the eNB has flexibility in use ofthese SRS in various functions, including PUSCH scheduling (e.g., RBallocation), UL rank assignments, UL MCS assignments, etc. For example,the eNB may determine to use the received precoded SRS for one aspect ofscheduling/assignment and the received unprecoded SRS for another aspectof scheduling/assignment based on existing channel conditions. Anycombination is possible in order to arrive at scheduling/assignmentaccording to embodiments of the present disclosure.

In addition, the eNB may provide instruction to the UE for PUSCHprecoding for data transmission. For example, after receiving bothprecoded SRS and unprecoded SRS from the UE, the eNB may determine thatthe UE will use the same precoding as was used for the precoded SRS. Inthat example, a single bit in a DL message may be used to signal the UEto use the same precoding for PUSCH data transmission. When the sameprecoding is not going to be used, then the eNB may not assert that bit.

In the bit is not asserted, the UE may further listen for additionalsignaling from the eNB identifying other precoding that the UE shoulduse for transmitting data in the PUSCH. In some examples, the eNB mayinclude the precoding data in full for use in PUSCH by the UE. A way toreduce signaling overhead is for the eNB to determine a delta betweenthe precoding used for the precoded SRS and the precoding for the PUSCHthat the eNB selects for the UE. The eNB may transmit that delta,instead of the full details of the precoding for the PUSCH, to the UE.This may provide more efficient use of resources as the signalingoverhead may be reduced as compared to the option of transmitting thefull amount of data. In turn, the UE receiving the delta information mayrecover the precoding for PUSCH by adding or multiplying the deltainformation with the precoding previously used for the SRS (whetheraddition or multiplication).

FIG. 1 illustrates a wireless communication network 100 in accordancewith various aspects of the present disclosure. The wirelesscommunication network 100 may include a number of UEs 102, as well as anumber of evolved Node Bs (eNodeB, or eNB) 104. The eNBs 104 may also bereferred to generally as base stations. An eNB 104 may also be referredto as an access point, base transceiver station, a node B, etc. An eNB104 may be a station that communicates with the UEs 102.

The eNBs 104 communicate with the UEs 102 as indicated by communicationsignals 106. A UE 102 may communicate with the eNB 104 via an uplink anda downlink. The downlink (or forward link) refers to the communicationlink from the eNB 104 to the UE 102. The uplink (or reverse link) refersto the communication link from the UE 102 to the eNB 104. The eNBs 104may also communicate with one another, directly or indirectly, overwired and/or wireless connections, as indicated by communication signals108.

UEs 102 may be dispersed throughout the wireless network 100, as shown,and each UE 102 may be stationary or mobile. The UE 102 may also bereferred to as a terminal, a mobile station, a subscriber unit, etc. TheUE 102 may be a cellular phone, a smartphone, a personal digitalassistant, a wireless modem, a laptop computer, a tablet computer, adrone, an entertainment device, a hub, a gateway, an appliance, awearable, peer-to-peer and device-to-device components/devices(including fixed, stationary, and mobile), Internet of Things (IoT)components/devices, and Internet of Everything (IoE) components/devices,etc. The wireless communication network 100 is one example of a networkto which various aspects of the disclosure apply.

Each eNB 104 may provide communication coverage for a particulargeographic area. In 3GPP, the term “cell” can refer to this particulargeographic coverage area of an eNB and/or an eNB subsystem serving thecoverage area, depending on the context in which the term is used. Inthis regard, an eNB 104 may provide communication coverage for a macrocell, a pico cell, a femto cell, and/or other types of cell. A macrocell generally covers a relatively large geographic area (e.g., severalkilometers in radius) and may allow unrestricted access by UEs withservice subscriptions with the network provider. A pico cell wouldgenerally cover a relatively smaller geographic area and may allowunrestricted access by UEs with service subscriptions with the networkprovider. A femto cell would also generally cover a relatively smallgeographic area (e.g., a home) and, in addition to unrestricted access,may also provide restricted access by UEs having an association with thefemto cell (e.g., UEs in a closed subscriber group (CSG), UEs for usersin the home, and the like).

An eNB for a macro cell may be referred to as a macro eNB. An eNB for apico cell may be referred to as a pico eNB. And, an eNB for a femto cellmay be referred to as a femto eNB or a home eNB. In the example shown inFIG. 1, the eNBs 104 a, 104 b and 104 c are examples of macro eNB forthe coverage areas 110 a, 110 b and 110 c, respectively (also referredto as cells herein). The eNBs 104 d and 104 e are examples of picoand/or femto eNBs for the coverage areas 110 d and 110 e, respectively.An eNB 104 may support one or multiple (e.g., two, three, four, and thelike) cells.

The wireless communication network 100 may also include relay stations.A relay station is a station that receives a transmission of data and/orother information from an upstream station (e.g., an eNB, a UE, or thelike) and sends a transmission of the data and/or other information to adownstream station (e.g., another UE, another eNB, or the like). A relaystation may also be a UE that relays transmissions for other UEs. Arelay station may also be referred to as a relay eNB, a relay UE, arelay, and the like. Some relays may also have UEcapabilities/functionalities.

The wireless communication network 100 may support synchronous orasynchronous operation. For synchronous operation, the eNBs 104 may havesimilar frame timing, and transmissions from different eNBs 104 may beapproximately aligned in time. For asynchronous operation, the eNBs 104may have different frame timing, and transmissions from different eNBs104 may not be aligned in time.

In some implementations, the wireless communication network 100 utilizesorthogonal frequency division multiplexing (OFDM) on the downlink andsingle-carrier frequency division multiplexing (SC-FDM) on the uplink.OFDM and SC-FDM partition the system bandwidth into multiple (K)orthogonal subcarriers, which are also commonly referred to as tones,bins, or the like. Each subcarrier may be modulated with data. Ingeneral, modulation symbols are sent in the frequency domain with OFDMand in the time domain with SC-FDM. The spacing between adjacentsubcarriers may be fixed, and the total number of subcarriers (K) may bedependent on the system bandwidth. For example, K may be equal to 72,180, 300, 600, 900, and 1200 for a corresponding system bandwidth of1.4, 3, 5, 10, 15, or 20 megahertz (MHz), respectively. The systembandwidth may also be partitioned into sub-bands. For example, asub-band may cover 1.08 MHz, and there may be 1, 2, 4, 8 or 16 sub-bandsfor a corresponding system bandwidth of 1.4, 3, 5, 10, 15, or 20 MHz,respectively.

According to embodiments of the present disclosure, the UEs 102 mayinclude both precoded SRS as well as unprecoded SRS in UL transmissionsto eNBs 104 (e.g., whether in periodic or aperiodic SRS uses). Theprecoding may involve weighting different antennas of a UE 102 differentamounts, so as to cause the UE 102 (an exemplary UE 102 in FIG. 1) tosteer its radiation pattern, or beam, in a particular (e.g., desired)direction. Additionally, the SRS precoding granularity may be wideband(same precoder applied across all tones) or narrow band (up to per toneprecoding). The unprecoded SRS refers to a SRS in which equal beamweights are applied to each antenna of a UE 102, so that no beamsteering occurs outside of the regular configuration of the antennas.

In some examples, the UE 102 may make the determination of the specificprecoding. For example, the UE 102 may receive one or more downlink (DL)reference signals, such as CSI-RS (channel state information-referencesignals), from an eNB 104 and, according to the channel quality of theDL channel determined from the reference signals, identify a directionthat is desirable in which to steer a beam of the UE 102. In otherexamples, the UE 102 may receive instruction from an eNB 104 on aprecoding to apply for an SRS (e.g., based on a measure of UL channelquality made at the eNB 104 with respect to one or more signals from theUE 102 and/or estimated from any other UE 102's signals).

The UE 102 may transmit the precoded SRS and the unprecoded SRS in theUL in a variety of ways. For example, the UE 102 may use a time divisionmultiplexing approach, such that both precoded SRS and unprecoded SRSare included in a same subframe, each using the same tone or band oftones at different time slots in the same subframe. Alternatively, theUE 102 may use a frequency division multiplexing approach, such thatboth the precoded SRS and unprecoded SRS are again included in a samesubframe, though with this approach each uses the same time slot butdifferent tones from among the available/selected frequency band withrespect to each other. As another alternative, the UE 102 may usedifferent resource slots (time and/or frequency) in different subframesto transmit the precoded SRS and unprecoded SRS—thus, one of the SRS(e.g., precoded) may be transmitted in a first subframe followed, in alater subframe, by the other SRS (e.g., unprecoded, or vice versa). Insome embodiments, the subframes may be contiguous to each other in time,while in other embodiments the subframes may have one or more othersubframes in between. Further, under any of the above-notedalternatives, each SRS is not limited as to which symbols in a givensubframe they are to be located.

Whatever the approach taken in transmitting both of the precoded SRS andthe unprecoded SRS, the eNB 104 receives both SRS types. With bothprecoded SRS and unprecoded SRS, the eNB 104 has flexibility in use ofthese SRS in various functions, including PUSCH scheduling (e.g., RBallocation), UL rank assignments, UL MCS assignments, etc. For example,the eNB 104 may determine to use the received precoded SRS for oneaspect of scheduling/assignment and the received unprecoded SRS foranother aspect of scheduling/assignment based on existing channelconditions—e.g., unprecoded SRS for RB allocation, precoded SRS for rankassignment, and both for MCS scheduling. This is just one example. Anycombination is possible in order to arrive at scheduling/assignmentaccording to embodiments of the present disclosure. For example, an SRSmay be used for several purposes, including sounding the UL channel forUL PUSCH scheduling at the eNB 104 and (where there is DL/UL channelsymmetricity, or it is at least assumed) for DL PDSCH scheduling.

Looking first at UL PUSCH scheduling, in embodiments the precoded SRSmay be used. Where the UE 102 has multiple transmit ports, an eNB 104may configure the UE 102 to sound multiple SRS (e.g., over differentsymbols as an example), each SRS with a different precoder. Then, theeNB 104 may measure the differently precoded SRS over different symbolsand select the best precoder (i.e., the precoded SRS with the bestmeasured characteristic from among the precoded SRSs measured). With theprecoder selected, the eNB 104 may signal the UE 102 to use thatselected precoder for UL PUSCH transmission.

Looking then at DL PDSCH scheduling, an unprecoded SRS may be used inembodiments. For example, the eNB 104 may seek to learn about thechannel to determine what the best precoder may be for DL PDSCHtransmission (e.g., to maximize throughput). In order to make thisdetermination, the eNB 104 may first determine properties of the rawchannel (i.e., unprecoded channel) for DL. After this, the eNB 104 mayapply singular vector decomponsition (SVD) or another approach, based onthe determined properties of the raw channel, to determine the bestprecoder for DL PDSCH transmission.

Accordingly, the UE 102 may transmit an unprecoded SRS, which the eNB104 measures and from which the eNB 104 obtains the raw channelproperties. The eNB 104 may assume that the DL raw channel is symmetricto the UL raw channel (e.g., with just a scalar difference due to UL/DLtransmit power imbalance), which assumption for example typically holdsfor a time division duplex system. Because of the assumption by the eNB104 in such embodiments that the learned UL raw channel is the same asthe DL raw channel with perhaps a scalar difference, the eNB 104 maydetermine a precoder for DL PDSCH transmission based on the raw ULchannel.

Further, the precoded SRS may be used for DL PDSCH scheduling. Thisrelates to whether the eNB 104 has knowledge of the UE 102's measuredcovariance matrix of interference plus noise. The unprecoded SRS may beused by the eNB 104 for DL PDSCH scheduling if the UE 102 feeds back tothe eNB 104 the measured interference plus noise covariance matrix. Forexample, where the UE 102 feeds back the measured interference plusnoise covariance matrix, the eNB 104 may use the unprecoded SRS todetermine the raw channel, calculate the whitening matrix based on thatmeasured interference plus noise, and determine the precoder for DLPDSCH transmission as discussed above.

If, however, the UE 102 does not feed back the measured covariancematrix of interference plus noise, then the eNB 104 may use the precodedSRS. For example, the UE 102 may set the precoder for the SRS to be thesame as the whitening matrix (e.g., the interference plus noise measuredat the UE 102) for the UE 102. The UE 102 may use the precoded SRS todeliver the whitened channel information to the eNB 104. Upon reachingthe eNB 104, the eNB 104 has information about the whitened channelbased on the precoded SRS. The eNB 104 may apply SVD on the whitenedchannel information to determine a precoder for DL PDSCH transmission.Thus, if the whitening is done by the eNB 104, then the unprecoded SRSmay be used to determine a precoder for DL PDSCH transmission, while ifwhitening is done at the UE 102, then the precoded SRS may be used todetermine a precoder for DL PDSCH transmission.

In addition to determining how to use the received precoded SRS andunprecoded SRS, an eNB 104 may provide instruction to UEs 102 for PUSCHprecoding for data transmission. For example, after receiving bothprecoded SRS and unprecoded SRS from an UE 102, an eNB 104 may determinethat the UE 102 will use the same precoding as was used for the SRS. Inthat example, a single bit in a DL message (e.g., in the DL controlchannel) may be used to signal the UE 102 (e.g., the bit asserted) touse the same precoding for PUSCH data transmission. When the sameprecoding is not going to be used, then the eNB 104 may not assert thatbit, which the UE 102 will interpret accordingly.

In that situation, the UE 102 may further listen for further signalingfrom the eNB 104 identifying other precoding that the UE 102 should usefor transmitting data in the PUSCH. In some examples, the eNB 104 mayinclude the precoding data for use in PUSCH by the UE 102. This mayconsume signaling overhead to an undesirable extent. To reduce thatsignaling overhead, the eNB 104 may determine a delta between theprecoding used for the SRS from the UE 102 and the precoding for thePUSCH that the eNB 104 selects for the UE 102. The eNB 104 may transmitthat delta, instead of the full details of the precoding for the PUSCH,to the UE 102. This may provide more efficient use of resources as thesignaling overhead may be reduced as compared to the other option. Inturn, the UE 102 receiving the delta information may recover theprecoding for PUSCH by adding or multiplying the delta information withthe precoding previously used for the SRS (whether addition ormultiplication is used may be configured previously between the eNB 104and UE 102, such as at device initialization or other time). Further,the eNB 104 may signal, during operation, the UE 102 to transition toone or the other (addition or multiplication).

FIG. 2 is a block diagram of an exemplary wireless communication device200 according to embodiments of the present disclosure. The wirelesscommunication device 200 may be a UE having any one of manyconfigurations described above. For purposes of example, wirelesscommunication device 200 may be a UE 102 as discussed above with respectto FIG. 1. The UE 102 may include a processor 202, a memory 204, an SRSmodule 208, a transceiver 210 (including a modem 212 and RF unit 214),and an antenna 216. These elements may be in direct or indirectcommunication with each other, for example via one or more buses.

The processor 202 may have various features as a specific-typeprocessor. For example, these may include a central processing unit(CPU), a digital signal processor (DSP), an application-specificintegrated circuit (ASIC), a controller, a field programmable gate array(FPGA) device, another hardware device, a firmware device, or anycombination thereof configured to perform the operations describedherein with reference to the UEs 102 introduced in FIG. 1 above. Theprocessor 202 may also be implemented as a combination of computingdevices, e.g., a combination of a DSP and a microprocessor, a pluralityof microprocessors, one or more microprocessors in conjunction with aDSP core, or any other such configuration.

The memory 204 may include a cache memory (e.g., a cache memory of theprocessor 302), random access memory (RAM), magnetoresistive RAM (MRAM),read-only memory (ROM), programmable read-only memory (PROM), erasableprogrammable read only memory (EPROM), electrically erasableprogrammable read only memory (EEPROM), flash memory, solid state memorydevice, hard disk drives, other forms of volatile and non-volatilememory, or a combination of different types of memory. In someembodiments, the memory 204 may include a non-transitorycomputer-readable medium. The memory 204 may store instructions 206. Theinstructions 206 may include instructions that, when executed by theprocessor 202, cause the processor 202 to perform operations describedherein with reference to a UE 102 in connection with embodiments of thepresent disclosure. The terms “instructions” and “code” may include anytype of computer-readable statement(s). For example, the terms“instructions” and “code” may refer to one or more programs, routines,sub-routines, functions, procedures, etc. “Instructions” and “code” mayinclude a single computer-readable statement or many computer-readablestatements.

The SRS module 208 may be used for various aspects of the presentdisclosure. The SRS module 208 may include various hardware componentsand/or software components to assist in determining what particularprecoding to use for the precoded SRS, as well as how to transmit boththe precoded SRS and the unprecoded SRS (e.g., using TDM, FDM, ordifferent subframes). In some embodiments, the SRS module 208 does notdetermine dynamically how to transmit, but rather checks its memory 204to determine what approach had been established previously with theserving eNB 104. This may also be referred to as a static approach. Inother embodiments, the SRS module 208 dynamically determines how totransmit (e.g., what precoding to use, what order to use, etc.). Forexample, upon receipt of CSI-RS (or some other RS) from its serving eNB104, may analyze channel conditions based on the received RS todetermine what precoding to use in the UL for the SRS. In yet otherembodiments, the eNB 104 may provide instruction on what precoding theUE 102 should use. Where the eNB 104 provides instruction on whatprecoding to use for the SRS, the SRS module 208 may control respectiveaspects of the UE 102 in order to implement that instruction.

As shown, the transceiver 210 may include the modem subsystem 212 andthe radio frequency (RF) unit 214. The transceiver 210 can be configuredto communicate bi-directionally with other devices, such as basestations 104 and/or other network elements. The modem subsystem 212 maybe configured to modulate and/or encode data according to a MCS, e.g., aLDPC coding scheme, a turbo coding scheme, a convolutional codingscheme, a polar coding scheme, etc. For example, this may be performedbased on an allocation/assignment provided from the eNB 104 in responseto the eNB 104's receipt of both the precoded SRS and unprecoded SRSpreviously. The RF unit 214 may be configured to process (e.g., performanalog to digital conversion or digital to analog conversion, etc.)modulated/encoded data from the modem subsystem 212 (on outboundtransmissions) or of transmissions originating from another source suchas an eNB 104. Although shown as integrated together in transceiver 210,the modem subsystem 212 and the RF unit 214 may be separate devices thatare coupled together at the UE 102 to enable the UE 102 to communicatewith other devices.

The RF unit 214 may provide the modulated and/or processed data, e.g.data packets (or, more generally, data messages that may contain one ormore data packets and other information) such as SRS and PUSCH data ofthe present disclosure, to the antenna 216 for transmission to one ormore other devices. The antenna 216 may further receive data messagestransmitted from other devices and provide the received data messagesfor processing and/or demodulation at the transceiver 210. Asillustrated, antenna 216 may include multiple antennas in a MIMOconfiguration of similar or different designs in order to sustainmultiple transmission links for such things as spatial diversity, forimplementation of precoding according to embodiments of the presentdisclosure.

FIG. 3 is a block diagram of an exemplary wireless communication device300 according to embodiments of the present disclosure. The wirelesscommunication device 300 may be an eNB having any one of manyconfigurations described above. For purposes of example, wirelesscommunication device 300 may be an eNB 104 as discussed above withrespect to FIG. 1. The eNB 104 may include a processor 302, a memory304, a resource scheduling module 308, a transceiver 310 (including amodem 312 and RF unit 314), and an antenna 316. These elements may be indirect or indirect communication with each other, for example via one ormore buses.

The processor 302 may have various features as a specific-typeprocessor. For example, these may include a CPU, a DSP, an ASIC, acontroller, an FPGA device, another hardware device, a firmware device,or any combination thereof configured to perform the operationsdescribed herein with reference to the eNBs 104 introduced in FIG. 1above. The processor 302 may also be implemented as a combination ofcomputing devices, e.g., a combination of a DSP and a microprocessor, aplurality of microprocessors, one or more microprocessors in conjunctionwith a DSP core, or any other such configuration.

The memory 304 may include a cache memory (e.g., a cache memory of theprocessor 302), RAM, MRAM, ROM, PROM, EPROM, EEPROM, flash memory, solidstate memory device, hard disk drives, other forms of volatile andnon-volatile memory, or a combination of different types of memory. Insome embodiments, the memory 304 may include a non-transitorycomputer-readable medium. The memory 304 may store instructions 306. Theinstructions 306 may include instructions that, when executed by theprocessor 302, cause the processor 302 to perform operations describedherein with reference to an eNB 104 in connection with embodiments ofthe present disclosure.

The resource scheduling module 308 may be used for various aspects ofthe present disclosure. The resource scheduling module 308 may includevarious hardware components and/or software components to assist inperforming UL PUSCH scheduling, such as RB allocation, UL rank, UL MCS,etc., upon receiving precoded SRS and unprecoded SRS from UEs 102(whether in the same subframe using TDM or FDM or different subframes).In making the determinations, the eNB 104 may use any combination of theprecoded SRS and unprecoded SRS. For example, in MU-MIMO situations, theeNB 104 may use the precoded/unprecoded SRS to determine how to bestconsider UEs 102 jointly, or individual UEs 102 when single UE-MIMOexists.

For example, the resource scheduling module 308 may determine to use thereceived precoded SRS for one aspect of scheduling/assignment and thereceived unprecoded SRS for another aspect of scheduling/assignmentbased on existing channel conditions—e.g., unprecoded SRS for RBallocation, precoded SRS for rank assignment, and both for MCSscheduling. Any combination is possible of the SRS in order to arrive atscheduling/assignment according to embodiments of the presentdisclosure.

Further, the resource scheduling module 308 may determine PUSCHprecoding parameters for the UE 102 and cause the transceiver 310 totransmit instruction regarding that determination to the UE 102. Forexample, after receiving both precoded SRS and unprecoded SRS from an UE102, the resource scheduling module 308 may determine that the UE 102will use the same precoding as was used for the SRS (e.g., because oneor more signal characteristics from the SRS (precoded and/or unprecoded)meet one or more target thresholds). In that example, the resourcescheduling module may set a single bit in a DL message (e.g., in the DLcontrol channel) to signal the UE 102 (e.g., the bit asserted) to usethe same precoding for PUSCH data transmission. When the same precodingis not going to be used, then the resource schedule module 308 may notset that bit (e.g., not asserted). Other approaches to signaling theprecoding determination may alternatively be used as well.

Where the resource scheduling module 308 determines that the sameprecoding will not be used for data transmission in the PUSCH, it maydetermine what precoding to assign the UE 102 to use for the data. Withthat determination, the resource scheduling module 308 may then send theindication of the PUSCH data precoding to the UE 102. In some examples,the resource scheduling module 308 may include the full precoding data(i.e., all parameters specified for the UE 102 to use) for use in PUSCHby the UE 102. In other examples, the resource scheduling module 308 mayreduce the signaling overhead involved by determining a delta betweenthe precoding used for the SRS by the UE 102 and the precodingdetermined for use for the PUSCH data. The resource scheduling module308 may cause the transceiver 310 transmit that delta, instead of thefull details of the precoding for the PUSCH, to the UE 102. This mayprovide more efficient use of resources as the signaling overhead may bereduced as compared to the other option. This may be a staticarrangement between the UE 102 and the eNB 104 (i.e., preset prior touse) or dynamic with appropriate signaling between the devices toidentify that the instruction is coming, and in what format.

As shown, the transceiver 310 may include the modem subsystem 312 andthe RF unit 314. The transceiver 310 can be configured to communicatebi-directionally with other devices, such as UEs 102 and/or othernetwork elements. The modem subsystem 312 may be configured to modulateand/or encode data according to a MCS, e.g., a LDPC coding scheme, aturbo coding scheme, a convolutional coding scheme, a polar codingscheme, etc. The RF unit 314 may be configured to process (e.g., performanalog to digital conversion or digital to analog conversion, etc.)modulated/encoded data from the modem subsystem 312 (on outboundtransmissions) or of transmissions originating from another source suchas a UE 102.

Although shown as integrated together in transceiver 310, the modemsubsystem 312 and the RF unit 314 may be separate devices that arecoupled together at the eNB 104 to enable the eNB 104 to communicatewith other devices. The RF unit 314 may provide the modulated and/orprocessed data, e.g. data packets (or, more generally, data messagesthat may contain one or more data packets and other information) to theantenna 316 for transmission to one or more other devices. The antenna316 may further receive data transmitted from other devices and providethe received data messages for processing and/or demodulation at thetransceiver 310. This may include, for example, receiving the precodedSRS and unprecoded SRS from UEs 102 and transmitting PUSCH dataprecoding assignments according to embodiments of the presentdisclosure. As illustrated, antenna 316 may include multiple antennas ina MIMO configuration of similar or different designs in order to sustainmultiple transmission links.

FIG. 4 shows a block diagram illustrating communication between twowireless communication devices of a MIMO system 400 in accordance withthe present disclosure. For sake of clarity in explanation, an eNB 104and a UE 102 are shown. However, it is understood that the followingdescription is applicable to communication between any two wirelesscommunication devices in accordance with the present disclosure.Further, the following discussion will focus on those aspects pertinentto the present disclosure; as will be recognized, the elements of FIG. 4may be further used for other purposes.

At the eNB 104, a transmit processor 420 may receive data from a datasource 410 and control information from a controller/processor 440. Thedata rate, coding, and modulation for each data stream may be determinedby instructions performed by processor 430. The transmit processor 420may process (e.g., encode and symbol map) the data and controlinformation to obtain data symbols and control symbols, respectively.This may include, for example, symbol mapping based on a particularmodulation scheme (e.g., BPSK, QSPK, M-PSK, or M-QAM). A transmit (TX)multiple-input multiple-output (MIMO) processor 430 may perform spatialprocessing (e.g., precoding) on the data symbols, the control symbols,and/or the reference symbols, if applicable, and may provide outputsymbol streams to the modulators (MODs) 432 a through 432 t.

Each modulator 432 may process a respective output symbol stream (e.g.,for OFDM, etc.) to obtain an output sample stream. Each modulator 432may further process (e.g., convert to analog, amplify, filter, andupconvert) the output sample stream to obtain a downlink signal.Downlink signals from modulators 432 a through 432 t may be transmittedvia antennas 434 a through 434 t, respectively. As some examples, theantennas 434 a through 434 t may transmit DCI, RS, and regular datawhere the eNB 104 is the one serving the UE 102 that is the targetedrecipient. Embodiments of the present disclosure include having multipleantennas.

At the UE 102, antennas 452 a through 452 r may receive the downlinksignals from the eNB 104 and may provide received signals to thedemodulators (DEMODs) 454 a through 454 r, respectively. Eachdemodulator 454 may condition (e.g., filter, amplify, downconvert, anddigitize) a respective received signal to obtain input samples. Eachdemodulator 454 may further process the input samples (e.g., for OFDM,etc.) to obtain received symbols. A MIMO detector 456 may obtainreceived symbols from all the demodulators 454 a through 454 r, performMIMO detection on the received symbols if applicable, and providedetected symbols. A receive processor 458 may process (e.g., demodulate,deinterleave, and decode) the detected symbols, provide decoded data forthe UE 102 (e.g., RS, regular data, and PUSCH data precoding as justsome examples pertinent to embodiments of the present disclosure), andprovide decoded control information to a controller/processor 480.

On the uplink, at the UE 102, a transmit processor 464 may receive andprocess data from a data source 462 and control information from thecontroller/processor 480. The data may include precoded SRS andunprecoded SRS, regular UL data precoded according to instructions fromthe eNB 104 and directed to the serving eNB 104, and/or connection setupor response information. The transmit processor 464 may also generateother reference symbols for a reference signal.

The symbols from the transmit processor 464 may be precoded by a TX MIMOprocessor 466, further processed by the modulators 454 a through 454 r(e.g., for SC-FDM, etc.), and transmitted to the eNB 104. For example,for the precoded SRS, the weights may be processed by the modulators 454a through 454 r to cause the MIMO antennas 452 a through 452 r. At theeNB 104, the uplink signals from the UE 102 may be received by theantennas 434, processed by the demodulators 432, detected by a MIMOdetector 436, if applicable, and further processed by a receiveprocessor 438 to obtain decoded data and control information sent by theUE 102 (e.g., precoded SRS and unprecoded SRS). The processor 438 mayprovide the decoded data to a data sink and the decoded controlinformation to the controller/processor 440.

The controllers/processors 440 and 480 may direct the operation at theeNB 104 and the UE 102, respectively. The controller/processor 440and/or other processors and modules at the eNB 104 may perform or directthe execution of various processes for the techniques described herein,including sending SRS precoding information (where applicable),determining UL PUSCH scheduling based on precoded SRS and unprecodedSRS, and PUSCH data precoding assignments, etc. Thecontrollers/processor 480 and/or other processors and modules at the UE102 may also perform or direct the execution of the various processesfor the techniques described herein, including determining particularSRS precoding parameters and determining PUSCH data precoding per eNB104 instruction.

In this regard, the memories 442 and 482 may store data and programcodes for the eNB 104 and the UE 102, respectively, to perform or directthe execution of these various processes. A scheduler 444 may schedulewireless communication devices for data transmission on the downlinkand/or uplink.

FIG. 5A is a block diagram of an exemplary uplink frame structure 500according to embodiments of the present disclosure. It provides anillustrative example of how an uplink subframe may be organized withrespect to precoded SRS and unprecoded SRS when relying on TDM fortransmitting both in a given subframe (whether using periodic oraperiodic SRS). A frame 502 may have a duration t (e.g., 10 ms) and maybe divided into some number of equally sized subframes (e.g., 10). Inother embodiments, the frame 502 may have a shorter duration (e.g., forhigher frequency/latency requirement uses to name just one example).

Each subframe may include consecutive time slots, such as two. Aresource grid may be used to represent two time slots, each time slotincluding a resource block (RB). Further, multiple RBs (e.g.,representing multiple groupings of subcarriers) may be grouped togetheras the RBGs mentioned above with respect to FIG. 1. The resource grid(illustrated in FIG. 5A with respect to a particular RB) may be dividedinto multiple resource elements. For a cyclic prefix (e.g., according toLTE), a resource block may contain 12 consecutive subcarriers in thefrequency domain and 7 consecutive OFDM symbols in the time domain, fora total of 84 resource elements. For an extended cyclic prefix, an RBmay contain 12 consecutive subcarriers in the frequency domain and 6consecutive OFDM symbols in the time domain, for a total of 72 resourceelements.

According to embodiments of the present disclosure, the precoding forthe SRS may be made on any of a variety of levels of granularity. Forexample, the precoding may be wideband, ranging down to narrowband(e.g., per tone precoding), with any value in between.

Some of the resource elements may include the UL SRS (precoded and/orunprecoded). In the example provided in FIG. 5A, both precoded SRS andunprecoded SRS are provided in the same subframe according to TDM, suchthat each may use the same band (depending on granularity) of tones(frequencies) but at different scheduled time slots in the subframe.FIG. 5A provides an example only—the precoded SRS and unprecoded SRS mayoccur at any symbols of the subframe (e.g., may occur during any timeslots designated therefore in the subframe).

The example particularly illustrated in FIG. 5A provides the first SRS504 at a first time slot and the second SRS 506 at a second time slotfollowing the first time slot. Although illustrated as being incontiguous time slots, the time slots used in the subframe may not becontiguous to each other. The first SRS 504 may be the precoded SRS andthe second SRS 506 the unprecoded SRS, or vice versa. The other resourceelements may include other control and/or data symbols for either UL,DL, or some combination of both.

FIG. 5B is a block diagram of an exemplary uplink frame structure 520according to alternative embodiments of the present disclosure. Itprovides an illustrative example of how an uplink subframe may beorganized with respect to precoded SRS and unprecoded SRS when relyingon FDM for transmitting both in a given subframe (whether using periodicor aperiodic SRS). For simplicity of discussion, the differences to FIG.5A will be emphasized.

In the example of FIG. 5B, both the precoded SRS and the unprecoded SRSare provided in the same subframe according to FDM, such that each mayuse the same time slot but different tones. Although illustrated asoccupying a single time slot, the shared time resource may extend tomore than one time slot, while still dividing up allocation of thefrequencies of the resource block between the precoded SRS andunprecoded SRS in the relevant time slot(s). Again, the other resourceelements may include other control and/or data symbols for either UL,DL, or some combination of both.

FIG. 5C is a block diagram of an exemplary uplink frame structure 540according to alternative embodiments of the present disclosure. Itprovides an illustrative example of how uplink subframes may beorganized with respect to precoded SRS and unprecoded SRS when relyingon use of multiple subframes for transmitting both (whether usingperiodic or aperiodic SRS). For simplicity of discussion, thedifferences to FIG. 5A/5B will be emphasized.

In the example of FIG. 5C, the precoded SRS and the unprecoded SRS areprovided in different subframes identified as subframe i for SRS1 504and subframe i+j for SRS2 506. The subframes may be adjacent to eachother in time (i.e., no intervening subframes between them) or not(i.e., one or more intervening subframes between them). The SRS1 504 maybe either the precoded SRS or the unprecoded SRS, with the SRS2 506being the other of the two. As illustrated, the SRS in each subframedoes not need to be assigned to the same time and/or frequency resourcesas the other (though such may be the case).

Turning now to FIG. 6, a flowchart is illustrated of an exemplary method600 for wireless communication in accordance with various aspects of thepresent disclosure. In particular, the method 600 illustrates thetransmitting of precoded SRS and unprecoded SRS according to embodimentsof the present disclosure. Method 600 may be implemented by a given UE102 (any number of UEs 102, with focus on one for simplicity ofdiscussion herein). It is understood that additional steps can beprovided before, during, and after the steps of method 600, and thatsome of the steps described can be replaced or eliminated from themethod 600.

At block 602, the UE 102 determines how to precode an SRS. This may bedone, for example, the UE 102 may receive one or more downlink (DL)reference signals, such as CSI-RS, from an eNB 104 and, according to thechannel quality of the DL channel determined from the reference signals,identify a direction that is desirable in which to steer a beam of theUE 102. Where the eNB 104 provides instruction on a precoding to applyfor SRS, the UE 102 may access that instruction at block 602.

At block 604, the UE 102 generates the precoded SRS according to theinformation determined from block 602.

At block 606, the UE 102 generates the unprecoded SRS. Althoughdescribed as occurring at a subsequent block to block 604, this mayoccur prior to or concurrent with block 604.

At decision block 608, if TDM is used for conveying the precoded SRS andunprecoded SRS to the eNB 104, then the method 600 proceeds to block610. As noted previously, whether to use TDM may have been establishedpreviously between the UE 102 and the eNB 104.

At block 610, the UE 102 places the precoded SRS and the unprecoded SRSinto the same subframe in different symbol periods. These may beadjacent time slots (symbol periods) or nonadjacent.

Returning to decision block 608, if TDM is not used, then the method 600may instead proceed to decision block 612.

At decision block 612, if FDM is used for conveying the precoded SRS andthe unprecoded SRS to the eNB 104, then the method 500 proceeds to block614.

At block 614, the UE 102 places the precoded SRS and the unprecoded SRSinto the same subframe in different tones (frequency elements) at thesame time slot (symbol period).

Returning to decision block 612, if FDM is not used, then the method 600may instead proceed to block 616.

At block 616, since TDM and FDM are not being used, the UE 102 placesthe precoded SRS and the unprecoded SRS into different subframes. Thesesubframes may be adjacent to each other or have one or more interveningsubframes. Further, the particular resource elements used in eachsubframe may vary from each other and over time.

From any of blocks 610, 614, or 616, the method 600 proceeds to block618.

At block 618, the UE 102 transmits the precoded SRS and the unprecodedSRS to the eNB 104 according to the approach taken to place the precodedSRS and unprecoded SRS into one or more subframes.

At block 620, the UE 102 may receive data precoding instruction from theeNB 104 for use in the PUSCH. Although illustrated as following each SRStransmission, multiple SRS transmissions may occur between precodingassignments for PUSCH data transmissions.

At decision block 622, if the data precoding instruction identifies thatthe UE 102 should use the same precoding as was used for the precodedSRS, then the method 600 proceeds to block 624. This may be identifiedby the setting of a given bit in a DL message from the eNB 104, whichthe UE 102 checks for in DL messages it receives.

At block 624, the UE 102 applies the same precoding as was used for theSRS to the antennas for use in transmission of data on the PUSCH to theeNB 104.

Returning to decision block 622, if the data precoding instruction doesnot identify that the same precoding should be used, then the method 600instead proceeds to decision block 626. This may be identified bychecking the DL messages for the bit in the header and that it is notset.

At decision block 626, the UE 102 proceeds with determining whether theeNB 104 uses delta signaling to identify the precoding to be used forPUSCH data. This may be determined by checking a procedure previouslyagreed upon between the devices or based upon an explicit identificationfrom the eNB 104 at the time that delta signaling is to be used. Ifdelta signaling is used, then the method 600 proceeds to block 628.

At block 628, the UE 102 obtains the delta information received from theeNB 104 and derives the data precoding to be used on the PUSCH data. Forexample, the UE 102 may recover the precoding for PUSCH by adding ormultiplying the delta information with the precoding previously used forthe SRS (whether addition or multiplication is used may be configuredpreviously between the eNB 104 and UE 102, such as at deviceinitialization or other time).

At block 630, the UE 102 applies the precoding derived from block 628for use in transmission of data on the PUSCH to the eNB 104.

Returning to decision block 626, if it is determined that the eNB 104did not use delta signaling, then the method 600 proceeds to block 632.

At block 632, the UE 102 extracts the explicitly identified precodingdata for use in PUSCH data by the UE 102. This may be extracted from aDL message from the eNB 104 that was received previously or at the time.

From any of blocks 624, 630, or 632, the method 600 proceeds to block634.

At block 634, the UE 102 transmits data on the PUSCH with precoding asdetermined from blocks 624, 630, or 632 as the case may be.

The above actions may repeat during operation (e.g., SRS eitherperiodically or aperiodically and likewise for the PUSCH precodingassignments).

Turning now to FIG. 7, a flowchart is illustrated of an exemplary method700 for wireless communication in accordance with various aspects of thepresent disclosure. In particular, the method 700 illustrates thereception and processing of precoded SRS and unprecoded SRS according toembodiments of the present disclosure. Method 700 may be implemented byan eNB 104 (any number of eNBs 104 in communication with any number ofUEs 102, focusing on one for simplicity of discussion here). It isunderstood that additional steps can be provided before, during, andafter the steps of method 700, and that some of the steps described canbe replaced or eliminated from the method 700.

At decision block 702, if the precoded SRS and unprecoded SRS are notreceived in the same subframe, then the method 700 proceeds to block704.

At block 704, the eNB 104 receives a first SRS in a first subframe. Forexample, the first SRS may be a precoded SRS. Alternatively, the firstSRS may be an unprecoded SRS.

At block 706, the eNB 104 receives a second SRS in a second subframethat occurs after the first subframe. For example, the second SRS may bean unprecoded SRS. Alternatively, the second SRS may be a precoded SRS(either way, one is unprecoded and the other precoded in respectivesubframes).

Returning to decision block 702, if the precoded SRS and unprecoded SRSare received in the same subframe, then the method 700 proceeds todecision block 708.

At decision block 708, if TDM is used then the method 700 proceeds toblock 710.

At block 710, the eNB 104 receives a first SRS in a first symbol periodof a given subframe. For example, the first SRS may be a precoded SRS.Alternatively, the first SRS may be an unprecoded SRS.

At block 712, the eNB 104 receives a second SRS in a second symbolperiod that is different from the first symbol period but still in thesame given subframe. For example, the second SRS may be an unprecodedSRS. Alternatively, the second SRS may be a precoded SRS.

Returning to decision block 708, if TDM is not used then the method 700proceeds to block 714.

At block 714, the eNB 104 receives a first SRS on a first set offrequency resources (tones) of a given subframe. For example, the firstSRS may be a precoded SRS. Alternatively, the first SRS may be anunprecoded SRS.

At block 716, the eNB 104 receives a second SRS on a second set offrequency resources different from the first set of frequency resourcesbut still in the same given subframe at time slot. For example, thesecond SRS may be an unprecoded SRS. Alternatively, the second SRS maybe a precoded SRS. Although blocks 714 and 716 are listed separately,these actions may occur together at the eNB 104 as each is received atthe same time slot(s), albeit at different frequency resources.

From any of blocks 706, 712, and 716, the method 700 proceeds to block718.

At block 718, the eNB 104 determines what data precode assignment forPUSCH to provide to the UE 102, and how to provide the assignment to theUE 102.

At decision block 720, if the same precoding assignment for PUSCH as wasused for the precoded SRS is made, then the method 700 proceeds to block722.

At block 722, the eNB 104 generates an indication for the UE 102 to usethe same precoding. For example, the eNB 104 may set a bit in a DLcontrol message (e.g., asserting it to indicate to use the sameprecoding).

Returning to decision block 720, if the same precoding assignment is notintended for the PUSCH, then the method 700 proceeds to decision block724.

At decision block 724, if the eNB 104 is using delta signaling toidentify the data precoding for PUSCH, then the method 700 proceeds toblock 726.

At block 726, the eNB 104 generates the delta between the target dataprecoding for PUSCH and the precoding that the UE 102 used for thepreviously received precoded SRS. This may be generated so that the UE102 uses addition to recreate the precoding assignment, or alternativelymultiplication depending on how previously established between theentities.

Returning to decision block 724, if the eNB 104 is not using deltasignaling to identify the data precoding for PUSCH, then the method 700proceeds to block 728.

At block 728, the eNB 104 generates a full identification of the dataprecoding for the PUSCH, which will be included in a DL message to theUE 102.

From any of blocks 722, 726, and 728, the method 700 proceeds to block730.

At block 730, the eNB 104 sends the data precode instruction to the UE102 for the UE 102 to use in UL PUSCH transmissions.

Information and signals may be represented using any of a variety ofdifferent technologies and techniques. For example, data, instructions,commands, information, signals, bits, symbols, and chips that may bereferenced throughout the above description may be represented byvoltages, currents, electromagnetic waves, magnetic fields or particles,optical fields or particles, or any combination thereof.

The various illustrative blocks and modules described in connection withthe disclosure herein may be implemented or performed with ageneral-purpose processor, a DSP, an ASIC, an FPGA or other programmablelogic device, discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. A general-purpose processor may be a microprocessor,but in the alternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices (e.g., a combinationof a DSP and a microprocessor, multiple microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration).

The functions described herein may be implemented in hardware, softwareexecuted by a processor, firmware, or any combination thereof. Ifimplemented in software executed by a processor, the functions may bestored on or transmitted over as one or more instructions or code on acomputer-readable medium. Other examples and implementations are withinthe scope of the disclosure and appended claims. For example, due to thenature of software, functions described above can be implemented usingsoftware executed by a processor, hardware, firmware, hardwiring, orcombinations of any of these. Features implementing functions may alsobe physically located at various positions, including being distributedsuch that portions of functions are implemented at different physicallocations.

Also, as used herein, including in the claims, “or” as used in a list ofitems (for example, a list of items prefaced by a phrase such as “atleast one of” or “one or more of”) indicates an inclusive list suchthat, for example, a list of [at least one of A, B, or C] means A or Bor C or AB or AC or BC or ABC (i.e., A and B and C). It is alsocontemplated that the features, components, actions, and/or stepsdescribed with respect to one embodiment may be structured in differentorder than as presented herein and/or combined with the features,components, actions, and/or steps described with respect to otherembodiments of the present disclosure.

As those of some skill in this art will by now appreciate and dependingon the particular application at hand, many modifications, substitutionsand variations can be made in and to the materials, apparatus,configurations and methods of use of the devices of the presentdisclosure without departing from the spirit and scope thereof. In lightof this, the scope of the present disclosure should not be limited tothat of the particular embodiments illustrated and described herein, asthey are merely by way of some examples thereof, but rather, should befully commensurate with that of the claims appended hereafter and theirfunctional equivalents.

What is claimed is:
 1. A method, comprising: receiving, by a firstwireless communications device, a precoded sounding reference signal(SRS) from a second wireless communications device; receiving, by thefirst wireless communications device, an unprecoded SRS separate fromthe precoded SRS from the second wireless communications device; anddetermining, by the first wireless communications device, a resourcescheduling for the second wireless communications device based on acombination of the precoded SRS and the unprecoded SRS.
 2. The method ofclaim 1, further comprising: transmitting, by the first wirelesscommunications device, a resource scheduling message comprising thedetermined resource scheduling to the second wireless communicationsdevice.
 3. The method of claim 1, wherein: the receiving the precodedSRS comprises receiving during a first symbol period of a subframe, andthe receiving the unprecoded SRS comprises receiving during a secondsymbol period of the subframe.
 4. The method of claim 1, wherein: thereceiving the precoded SRS comprises receiving during a symbol period ofa subframe using a first plurality of frequency resources, and thereceiving the unprecoded SRS comprises receiving during the symbolperiod of the subframe using a second plurality of frequency resourcesdifferent from the first plurality of frequency resources.
 5. The methodof claim 1, wherein: the receiving the precoded SRS comprises receivingthe precoded SRS during a first subframe, and the receiving theunprecoded SRS comprises receiving the unprecoded SRS during a secondsubframe after the first subframe.
 6. The method of claim 1, furthercomprising: generating, by the first wireless communications device, aprecode instruction for the second wireless communications device fordata transmission on an uplink channel.
 7. The method of claim 6,wherein the precode instruction directs the second wirelesscommunications device to apply a precoding used for the precoded SRS fordata transmission.
 8. The method of claim 6, wherein the generatingfurther comprises: determining, by the first wireless communicationsdevice, a delta between a desired precoding and an existing precodingused for the precoded SRS; and including, by the first wirelesscommunications device, the delta as the precode instruction.
 9. Anapparatus, comprising: a transceiver configured to: receive a precodedsounding reference signal (SRS) from a wireless communications device;and receive an unprecoded SRS separate from the precoded SRS from thewireless communications device; and a processor configured to determinea resource scheduling for the second wireless communications devicebased on a combination of the precoded SRS and the unprecoded SRS. 10.The apparatus of claim 9, wherein the transceiver is further configuredto: transmit a resource scheduling message comprising the determinedresource scheduling to the wireless communications device.
 11. Theapparatus of claim 9, wherein: the transceiver is configured to receivethe precoded SRS during a first symbol period of a subframe, and thetransceiver is configured to receive the unprecoded SRS during a secondsymbol period of the subframe.
 12. The apparatus of claim 9, wherein:the transceiver is configured to receive the precoded SRS during asymbol period of a subframe using a first plurality of frequencyresources, and the transceiver is configured to receive the unprecodedSRS during the symbol period of the subframe using a second plurality offrequency resources different from the first plurality of frequencyresources.
 13. The apparatus of claim 9, wherein the processor isfurther configured to: generate a precode instruction for the wirelesscommunications device for data transmission on an uplink channel. 14.The apparatus of claim 13, wherein the processor is further configuredto: determine a delta between a desired precoding and an existingprecoding used for the precoded SRS; and include the delta as theprecode instruction.
 15. A non-transitory computer-readable mediumhaving program code recorded thereon, the program code comprising: codefor causing a first wireless communications device to receive a precodedsounding reference signal (SRS) from a second wireless communicationsdevice; code for causing the first wireless communications device toreceive an unprecoded SRS separate from the precoded SRS from the secondwireless communications device; and code for causing the first wirelesscommunications device to determine a resource scheduling for the secondwireless communications device based on a combination of the precodedSRS and the unprecoded SRS.
 16. The non-transitory computer-readablemedium of claim 15, the code further comprising: code for causing thefirst wireless communications device to transmit a resource schedulingmessage comprising the determined resource scheduling to the secondwireless communications device.
 17. The non-transitory computer-readablemedium of claim 15, wherein: the code for causing the first wirelesscommunication device to receive the precoded SRS comprises receiptduring a first symbol period of a subframe, and the code for causing thefirst wireless communication device to receive the unprecoded SRScomprises receipt during a second symbol period of the subframe.
 18. Thenon-transitory computer-readable medium of claim 15, wherein: the codefor causing the first wireless communication device to receive theprecoded SRS comprises receipt during a symbol period of a subframeusing a first plurality of frequency resources, and the code for causingthe first wireless communication device to receive the unprecoded SRScomprises receipt during the symbol period of the subframe using asecond plurality of frequency resources different from the firstplurality of frequency resources.
 19. The non-transitorycomputer-readable medium of claim 15, the code further comprising: codefor causing the first wireless communications device to generate aprecode instruction for the second wireless communications device fordata transmission on an uplink channel.
 20. The non-transitorycomputer-readable medium of claim 19, wherein the code for causing thegenerating further comprises: code for causing the first wirelesscommunications device to determine a delta between a desired precodingand an existing precoding used for the precoded SRS; and code forcausing the first wireless communications device to include the delta asthe precode instruction.